A. Field of the Invention
The present invention relates to crop-spraying equipment and more particularly to a nozzle which is secured to a boom fixed aircraft used to spray or dust crops.
Typically, in a fixed-wing aircraft, the boom is secured to the trailing edge of the wings. The boom incorporates a plurality of spray nozzles affixed thereto and serves as a passageway for a liquid pesticide or economic poison which is discharged through the nozzles for spreading over a swath of crops, timber, other agricultural products or pest habitats. If a helicopter rather than a fixed-wing aircraft is used, the boom is attached to the fuselage or body of the craft.
The spray nozzle of the present invention is designed to correctly apply various pesticides to growing agricultural products. In order for correct application to occur, the "drift" must be accurately controlled. Drift refers to the spreading out of a released pesticide from a spray nozzle. Drift may occur from a complex of indicia, i.e., speed and attitude of the aircraft, wind conditions, the rate of discharge from the spray nozzle, etc. The present invention is directed to providing a spray droplet of relatively constant size issuing from the nozzle so that the drift may be readily controlled.
Accordingly, the spray nozzle of the present invention is adapted to be mounted upon a boom and incorporates a flexible diaphragm for allowing pesticide to be channeled into one of a plurallty of selectively adjustable orifices located in a rotatably arranged discharge device. After the liquid pesticide passes through such a selected orifice at a predetermined flow rate, it is directed through a flexible connecting tube to a rotating cage dispenser. The rotating cage dispenser is actuated by means of air flow striking fan blades arranged on the dispenser. The dispenser further comprises a meshed cylindrical cage assembly driven by the fan blades. The meshed cage determines the droplet size of spray to be discharged during rotation of the case assembly. Centrifugal force propels the pesticide through the meshed cage during rotation thereof.
It has been found that by controlling the quantity of spray and the droplet size, the drift of spray issuing from a nozzle may also be correspondingly controlled. Some or all of the following methods of control may also be employed with regulating quantity of spray and droplet size to further enhance control of drift: (1) using foam as a spray material; (2) rearranging nozzle location; (3) varying flying attitude; (4) compensating for meterological conditions; (5) redesigning mechanical nozzle, and (6) using stringing or polymerizing agents.
B. Description of the Prior Art
Prior art devices have dealt extensively with providing various types of valves to be used in spray nozzles. One such prior art device is disclosed in U.S. Pat. No. 2,639,194 which describes an anti-drip valve for spray nozzles. The valve utilizes a rubber diaphragm which is actuated by pressure from a liquid to be sprayed. The diaphragm is displaced from a closing position over a tube to permit spray to be channeled through the tube into a strainer and outwardly through a discharge passageway. While the diaphragm provides for an efficient sealing construction to prevent dripping of spray from the nozzle, there is no disclosure of providing an adjustable metering device for varying the rate of discharge of liquid spray. Thus, such a valve would not enable a spray nozzle to have the capability of selectively varying droplet size of a sprayed pesticide and therefore would not permit the control of spray drift from a nozzle.
An adjustable turret spray nozzle is disclosed in U.S. Pat. No. 3,596,835. Here, a spray nozzle is employed as part of a crop spraying system and incorporates a rotatable plate having a plurality of differently sized orifices for alignment with a discharge passage of a spray nozzle. A passage leads from a liquid spray source to spiral passageways which impart a turbulent flow to the liquid being discharged through a selected orifice in the rotatable plate. Thus, a rather small amount of liquid spray may be discharged in a spiral swirling path by means of the spiral passageways. However, this patent does not disclose a rotating cage assembly used in conjunction with the orifices in the rotatable plate. Therefore, it is apparent that the adjustable turret spray nozzle would not dispense insecticides or emulsions over relatively wide areas of crops or terrain.
A device for dispensing spray from a moving vehicle which incorporates a propeller driven hollow chamber is disclosed in U.S. Pat. No. 3,398,893. This patent describes the use of a meshed screen which is rotatably driven by a propeller. The propeller is activated by air flow impinging thereon when a vehicle is moving at a certain speed. The material to be sprayed is directly passed from a source through a tube into the rotating spray dispenser. It is apparent that this spray dispensing device does not enable the specific rate of discharge of spray material to be adjustably controlled unless there is an exchange of differently sized rotatable meshed spray dispenser chambers.